Viii-Direct Drive Supply Air Inverter - Lennox LGM Series Manual

L14 Reheat Coil Solenoid Valve
When Unit Controller input (Unit Controller J298-5 or
J299-8) indicates room conditions require dehumidifica­
tion, L14 reheat valve is energized (Unit Controller P269-3)
and refrigerant is routed to the reheat coil.
Reheat Setpoint
Reheat is factory-set to energize when indoor relative hu­
midity rises above 60% (default). The reheat setpoint can
be adjusted by changing Unit Controller Settings - Control
menu. A setting of 100% will operate reheat from an energy
management system digital output. The reheat setpoint
can also be adjusted using an optional Network Control
Panel (NCP).
Reheat will terminate when the indoor relative humidity falls
3% (57% default) or the digital output de-energizes. The re­
heat deadband can be adjusted at Settings - Control menu.
Check-Out
Test Hot Gas Reheat operation using the following proce­
dure.
1- Make sure reheat is wired as shown in wiring section.
2- Make sure unit is in local thermostat mode.
3- Select Unit Controller Service - Test.
The blower and compressor 1 (reheat) should be operat­
ing. Reheat mode will be appear on the Unit Controller dis­
play.
4- Deselect Unit Controller Service - Test.
Compressor 1 (reheat) and blower should de-energize.
Default Reheat Operation
TABLE 22
Reheat Operation - Two Cooling Stages - Default
T'stat and Humid­
ity Demands
Reheat Only Compressor 1 Reheat
Compressor 1 & 2 Enhanced Dehu­
Reheat & Y1
midification at Low CFM
Reheat & Y1 & Compressor 1 & 2 Enhanced Dehu­
Y2 midification at High CFM
*If there is no reheat demand and outdoor air is suitable,
free cooling will operate.
**If there is no reheat demand and outdoor air is suitable,
free cooling and compressor 1 will operate.

VIII-Direct Drive Supply Air Inverter

If a test and balance contractor has not commissioned the
unit, use this section to set supply air CFM.
A-Set Blower Speed
1- Use table 23 to fill in field-provided, design specified
blower CFM.
Operation
Page 49
TABLE 23
Blower CFM Design Specifications
Blower Speed
Heating
Cooling High
Cooling Low
Ventilation
2- Use the following menu to enter the blower design
specified CFM into the Unit Controller. Don't press
"SAVE" until all CFM are entered. Make sure blower
CFM is within limitations shown in table 24. Refer to the
Unit Controller manual provided with unit.
SETUP > TEST & BALANCE > BLOWER
3- Once all four speeds are entered, the target (highest of
the heating and cooling settings) CFM and default
RPM will be displayed.
Note - When units are not equipped with heat, the Blower
Heat speed will not be displayed. Blower Cooling High will
be the first blower speed to appear.
4- Measure the static pressure as shown in the Blower
Start-Up section. Use the static pressure, target CFM
and blower tables to determine the RPM needed. Val­
ues in the blower table reflect the static pressures tak­
en in locations shown in figure 13.
5- Enter the RPM and repeat the previous step until the
design CFM is reached.
6- Press SAVE followed by MAIN MENU.
Note - Once the CFM settings are saved, the Unit Controller
will set all other blower CFM.
B-Set Damper Minimum Position
To maintain required minimum ventilation air volumes
when the unit is in the occupied mode, two minimum
damper positions must be set. The Unit Controller will open
the dampers to "Min OCP Blwr Low" when blower CFM is
BELOW a "midpoint" CFM. The Unit Controller will open the
damper to "Min OCP Blwr High" when blower CFM is at or
ABOVE the "midpoint" CFM.
The Unit Controller will calculate the "midpoint" CFM.
Set Minimum Position 1
Use the following menu in the Unit Controller to set "Min
OCP Blwr Low" for the blower CFM below the "midpoint"
CFM. When navigating into this menu, the Unit Controller
will bring on the corresponding blower speed and allow
damper position adjustment.
SETTINGS > RTU Options > EDIT PARAMETER > EN­
TER DATA ID - 9 > MIN DAMPER LOW BLOWER = X.X
Measure the intake air CFM. If the CFM is lower than the
design specified CFM for ventilation air, use the Unit Con­
troller to increase the damper percent open. If the CFM is
higher than specified, decrease the damper percent open.
Design
Specified CFM
%